Blog 7 Group 1

1. Force sensing resistor gives a resistance value with respect to the force that is applied on it. Try different loads (Pinching, squeezing with objects, etc.) and write down the resistance values. (EXPLAIN with TABLE)

Pressure	Resistance
No force	0 Ω
Light force	.5 kΩ
Forceful	2.0 Ω
Max force	1.1 Ω

Table 1: Shows the resistance values with different pressure 

2. 7 Segment display:
a. Check the manual of 7 segment display. Pdf document’s page 5 (or in the document page 4) circuit B is the one we have. Connect pin 3 or pin 14 to 5 V. Connect a 330 Ω resistor to pin 1. Other end of the resistor goes to ground. Which line lit up? Using package dimensions and function for B (page 4 in pdf), explain the operation of the 7 segment display by lighting up different segments. (EXPLAIN with VIDEO).

Video 1: Shows how the 7 segment display works while moving a resistor. 

b. Using resistors for each segment, make the display show 0 and 5. (EXPLAIN with PHOTOs)

Figure 1: Shows 5 on the 7 segment display

Figure 2:  Shows 0 on the 7 segment display

3. Display driver (7447). This integrated circuit (IC) is designed to drive 7 segment display through resistors. Check the data sheet. A, B, C, and D are binary inputs. Pins 9 through 15 are outputs that go to the display. Pin 8 is ground and pin 16 is 5 V.
a. By connecting inputs either 0 V or 5 V, check the output voltages of the driver. Explain how the inputs and outputs are related. Provide two different input combinations. (EXPLAIN with PHOTOs and TRUTH TABLE)

Figure 3: Shows 0 using the display driver

Figure 4: Shows 4 on the display driver

Display:	D	C	B	A
0	0	0	0	0
4	0	1	0	0

b. Connect the display driver to the 7 segment display. 330 Ω resistors need to be used between the display driver outputs and the display (a total of 7 resistors). Verify your question 3a outputs with those input combinations. (EXPLAIN with VIDEO)

Video 2:  Shows the different outputs from the display driver

4. 555 Timer:

a. Construct the circuit in Fig. 14 of the 555 timer data sheet. VCC = 5V. No RL (no connection to pin 3). RA = 150 kΩ, RB = 300 kΩ, and C = 1 µF (smaller sized capacitor). 0.01 µF capacitor is somewhat larger in size. Observe your output voltage at pin 3 by oscilloscope. (Breadboard and Oscilloscope PHOTOs)

Figure 5: Shows the setup for the 555 timer

Figure 6: Shows the output to the oscilloscope

b. Does your frequency and duty cycle match with the theoretical value? Explain your work.

Theoretical:
frequency: 1.44/((150,000+2*300,000)*1 e-6 = 1.92
duty cycle: 300,000/(150,000+2*300,000) = 0.4

Measured:
frequency: 1.4 Hz
duty cycle: 0.6

c. Connect the force sensing resistor in series with RA. How can you make the circuit give an output? Can the frequency of the output be modified with the force sensing resistor? (Explain with VIDEO)

Video 3:  Shows the 555 timer with the force sensing resistor.

5. Binary coded decimal (BCD) counter (74192). This circuit generates a 4-bit counter. With every clock change, output increases; 0000, 0001, 0010, …, 0111, 1000, 1001. But after 1001 (which is decimal 9), it goes back to 0000. That way, in decimal, it counts from 0 to 9. Outputs of 74192 are labelled as QA (Least significant bit), QB, QC, and QD (Most significant bit) in the data sheet (decimal counter, 74192). Use the following connections:

5 V: pins 4, 11, 16.

0 V (ground): pins 8, 14.

10 µF capacitor between 5 V and ground.

a. Connect your 555 timer output to pin 5 of 74192. Observe the input and each output on the oscilloscope. (EXPLAIN with VIDEO and TRUTH TABLE)

Counter	Qd	Qc	Qb	Qa
0	0	0	0	0
1	0	0	0	1
2	0	0	1	0
3	0	0	1	1
4	0	1	0	0
5	0	1	0	1
6	0	1	1	0
7	0	1	1	1
8	1	0	0	0

Figure 7: Shows the Truth table for the 74192

Video 4: Shows the frequency changes with different outputs 

6. 7486 (XOR gate). Pin diagram of the circuit is given in the logic gates pin diagram pdf file. Ground pin is 7. Pin 14 will be connected to 5 V. There are 4 XOR gates. Pins are numbered. Connect a 330 Ω resistor at the output of one of the XOR gates.

a. Put an LED in series to the resistor. Negative end of the LED (shorter wire) should be connected to the ground. By choosing different input combinations (DC 0V and DC 5 V), prove XOR operation through LED. (EXPLAIN with VIDEO)

Video 5: Shows how the XOR gate works.

b. Connect XOR’s inputs to the BCD counters C and D outputs. Explain your observation. (EXPLAIN with VIDEO)

Video 6: Shows what happens when the XOR is connected to the 74192

c. For 6b, draw the following signals together: 555 timer (clock), A, B, C, and D outputs of 74192, and the XOR output. (EXPLAIN with VIDEO)

Video 7: Shows the signal outputs

7. Connect the entire circuit: Force sensing resistor triggers the 555 timer. 555 timer’s output is used as clock for the counter. Counter is then connected to the driver (Counter’s A, B, C, D to driver’s A, B, C, D). Driver is connected to the display through resistors. XOR gate is connected to the counter’s C and D inputs as well and an LED with a resistor is connected to the XOR output. Draw the circuit schematic. (VIDEO and PHOTO)

Video 8:  Shows the whole circuit

Blog 6 group 1

1. You will use the OPAMP in “open-loop” configuration in this part, where input signals will be applied directly to the pins 2 and 3.

a. Apply 0 V to the inverting input. Sweep the non-inverting input (Vin) from -5 V to 5 V with 1 V steps. Take more steps around 0 V (both positive and negative). Create a table for Vin and Vout. Plot the data (Vout vs Vin). Discuss your results. What would be the ideal plot?

Vin	Vout
-5	-3.97
-4	-3.97
-3	-3.97
-2	-3.97
-1	-3.97
0	0
1	4.49
2	4.49
3	4.49
4	4.49
5	4.49

Table 1: Vin vs Vout for non-inverting

Graph 1: Shows Vin vs Vout on the non-inverting

Our values received make sense because the amplifier has a higher gain but a restriction on voltage.  So the values are going to increase close to the 5V right away because the gain amplifies it.

b. Apply 0 V to the non-inverting input. Sweep the inverting input (Vin) from -5 V to 5 V with 1 V steps. Take more steps around 0 V (both positive and negative). Create a table for Vin and Vout. Plot the data (Vout vs Vin). Discuss your results. What would be the ideal plot?

Vin	Vout
-5	4.49
-4	4.49
-3	4.49
-2	4.49
-1	4.49
0	0
1	-3.98
2	-3.98
3	-3.98
4	-3.98
5	-3.98

Table 2: Shows Vout vs Vin for the inverting

Graph 2: Shows Vout vs Vin on the inverting

Our values received make sense because the amplifier has a higher gain but a restriction on voltage.  So the values are going to increase close to the 5V right away because the gain amplifies it. But since this one is inverting, the negative input gives a positive output and vice versa.

2. Create a non-inverting amplifier. (R2 = 2 kΩ, R1 = 1 kΩ). Sweep Vin from -5 V to 5 V with 1 V steps. Create a table for Vin and Vout. Plot the measured and calculated data together.

Vin	Vout
-5	-4.24
-4	-4.24
-3	-4.24
-2	-4.24
-1	-2.73
-0.5	-1.56
0	0
0.5	1.56
1	2.73
2	4.24
3	4.24
4	4.24
5	4.24

Table 3: Shows Vin vs Vout with the resistors

Graph 3: Shows Vin vs Vout with the resistors

3. Create an inverting amplifier. (Rf = 2 kΩ, Rin = 1 kΩ). Sweep Vin from -5 V to 5 V with 1 V steps. Create a table for Vin and Vout. Plot the measured and calculated data together.

Vin	Vout
-5	4.2
-4	4.2
-3	4.21
-2	4.2
-1	2.152
-0.5	1.061
0	0
0.5	-1.031
1	-2.2
2	-3.8
3	-3.8
4	-3.8
5	-3.8

Table 4: Shows Vin vs Vout with the resistors

Graph 4: Shows Vin vs Vout with the resistors

4. Explain how an OPAMP works. How come is the gain of the OPAMP in the open loop configuration too high but inverting/non-inverting amplifier configurations provide such a small gain?
OPAMP works by not allowing any resistance to divide the gain.  It has two inputs of opposite polarity and has a single output with a very high gain.

RELAY:
1. Connect your DC power supply to pin 2 and ground pin 5. Set your power supply to 0V. Switch your multimeter to measure the resistance mode; use your multimeter to measure the resistance between pin 4 and pin 1. Do the same measurement between pin 3 and pin 1. Explain your findings (EXPLAIN).
When measuring the resistance between the pins, 4 and 1 received a value of 6.5 ohms, and pins 3 and 1 overloaded the circuit.  Since Vout on pin 4 is based off of the Vin being less then the threshold, since there is no voltage being inputted, Vin will receive a value on pin 4.

2. Now sweep your DC power supply from 0V to 8V and back to 0V. What do you observe at the multimeter (resistance measurements similar to #1)? Did you hear a clicking sound? How many times? What is the “threshold voltage values” that cause the “switching?” (EXPLAIN with a VIDEO).

Video 1: Shows when the relay threshold takes place

When increasing the voltage, you hear a single clicking noise from the relay around 5 Volts.  When turning the voltage back you hear another clicking noise around 2.5 Volts.  

3. How does the relay work? Apply a separate DC voltage of 5 V to pin 1. Check the voltage value of pin 3 and pin 4 (each with respect to ground) while switching the relay (EXPLAIN with a VIDEO).

Video 2: Shows when the relay switches and how it works

A relay works kind of like a transistor, you have to reach a certain voltage before anything changes.  Our threshold changes at 5V and 2.5V.  So pin 3 and 4 will swap values once the relay switches.

LED+RELAY:

Video 3: Shows how the relay works with a diode

The diode activated once the relay is switched when you hit 5V, and is switched off once you drop back below the lower threshold of 2.5V.

OPERATIONAL AMPLIFIER:

1. Connect the power supplies to the op-amp (+10V and 0V). Show the operation of LM 124 operational amplifier in DC mode with a non-inverting amplifier configuration. Choose any opamp in the IC. Method: Use several R1 and R2 configurations and change your input voltage (voltages between 0 and 10V) and record your output voltage. (EXPLAIN with a TABLE)

Input	Output V (R1=2K R2=1K	Output V (R1=1K R2=1K	Output V (R1=120 R2=1K
1	1.5	2	8
2	3	3.78	8.46
3	4.5	5.9	8.58
4	5.8	7.8	8.58
5	8	8.58	8.58
6	8.58	8.58	8.58
7	8.58	8.58	8.58
8	8.58	8.58	8.58
9	8.58	8.58	8.58
10	8.58	8.58	8.58